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Can livestock farming reduce its emissions?

Climate: “Reducing emissions means reducing our consumption of animal products”

Anaïs Marechal, science journalist
On April 6th, 2022 |
4 mins reading time
2
Climate: “Reducing emissions means reducing our consumption of animal products”
Sylvain_Pellerin
Sylvain Pellerin
Research Director at Inrae
Key takeaways
  • In 2010, the production of meat and dairy products contributed to the emission of 9.8 billion tonnes (Gt) of CO2 equivalent, or 20% of anthropogenic greenhouse gas (GHG) emissions from all sectors combined.
  • Land-use changes, such as deforestation in the Amazon to plant soybeans, account for more than a third of GHG emissions from animal feed.
  • Current crop production systems are highly specialised. One of the levers that could help reduce GHG emissions would be more diversified agriculture.
  • The worst thing would be to reduce livestock farming in France while continuing to eat as much meat as we import.

What is the climate footprint of livestock feed?


Accord­ing to one recent study1, in 2010 the pro­duc­tion of meat and dairy prod­ucts con­tributed to the emis­sion of 9.8 bil­lion tonnes (Gt) of CO2 equiv­a­lent, i.e. 20% of anthro­pogenic green­house gas (GHG) emis­sions from all sec­tors com­bined. 58% (5.8 Gt CO2 equiv­a­lent) of these emis­sions are due to the pro­duc­tion of ani­mal feed. They are explained on the one hand by the emis­sions from the agri­cul­tur­al plots of land, notably due to the use of fer­tilis­ers (3.7 Gt CO2 equiv­a­lent); and on the oth­er hand by changes in land use (2.1 Gt CO2 equiv­a­lent), for exam­ple when forests are cleared for soya production.

Dif­fer­ent assess­ments for dif­fer­ent mod­els
Account­ing for agri­cul­ture’s car­bon foot­print is still fraught with uncer­tain­ty, and fig­ures vary depend­ing on the para­me­ters and mod­els cho­sen. Using its Glob­al Live­stock Envi­ron­men­tal Assess­ment mod­el, the Food and Agri­cul­ture Orga­ni­za­tion of the Unit­ed Nations2 esti­mates that live­stock pro­duc­tion is respon­si­ble for 8.1 Gt of CO2 equiv­a­lent, and that ani­mal feed con­tributes 41% of glob­al live­stock emis­sions, totalling 3.3 Gt of CO2 equivalent.

These fig­ures show us that when we import soya to feed live­stock, it is not the trans­porta­tion that weighs most heav­i­ly on the cli­mate bal­ance, but land use change. Defor­esta­tion of the Ama­zon rain­for­est to grow soy­beans is reduc­ing the car­bon stock of these forests and con­tribut­ing to the nitro­gen sur­plus­es in our soils from ani­mal waste.

How can we successfully reduce greenhouse gas emissions from animal feed?

The most impor­tant tool is to reduce the amount of ani­mal prod­ucts in our diet. I would stress the notion of reduc­tion, not elim­i­na­tion: live­stock farm­ing pro­vides many ser­vices by mak­ing use of oth­er­wise unus­able land, by pro­mot­ing nitro­gen trans­fers between grass­lands and crops, by pro­duc­ing organ­ic fer­tilis­ers that lim­it the use of syn­thet­ic fer­tilis­ers, etc.

Land use changes account for more than a third of the GHG emis­sions from ani­mal feed: reduc­ing ani­mal feed pro­duc­tion reduces this share. The land freed up can then be refor­est­ed or used to pro­duce plant pro­teins for human con­sump­tion. More land is used for the pro­duc­tion of ani­mal feed than for human food: on aver­age 6 plant calo­ries are need­ed to pro­duce 1 ani­mal calo­rie. Pro­duc­tion for human con­sump­tion is there­fore more inter­est­ing from a cli­mat­ic point of view.

Can we still imagine other, more climate-friendly, livestock systems?

Anoth­er impor­tant mea­sure is based on a more sys­temic lev­el. It is a ques­tion of com­bin­ing ani­mal and plant pro­duc­tion and encour­ag­ing syn­er­gies between these two sec­tors. Cur­rent crop pro­duc­tion sys­tems are high­ly spe­cialised, and it is nec­es­sary to diver­si­fy crops to make the agro-eco­log­i­cal tran­si­tion a suc­cess. For exam­ple, tem­po­rary grass­lands and fod­der legumes can be intro­duced into maize and wheat rota­tions, and ani­mals can be raised near­by. This makes it pos­si­ble to relo­cate the pro­duc­tion of ani­mal feed, but not only that: legumes bring nitro­gen to the soil and reduce the need for syn­thet­ic fer­tilis­ers (the man­u­fac­ture of which emits CO2 and the spread­ing of N2O).

How­ev­er, the intro­duc­tion of fod­der legumes into rota­tions reduces the pro­duc­tion of cere­als for human con­sump­tion: these devel­op­ments must go hand in hand with con­sumer food demand.

Are there technical means of reducing the carbon footprint of animal feed? 

Yes, they are more at the farm lev­el. They are based on the opti­mi­sa­tion of ani­mal rations. For exam­ple, there is pre­ci­sion ani­mal feed­ing or genet­ic selec­tion of indi­vid­u­als that make bet­ter use of feed. Graz­ing prac­tices, such as rota­tion­al graz­ing, also make it pos­si­ble to make bet­ter use of the grass avail­able in the meadows.

One of the areas of progress high­light­ed is the opti­mi­sa­tion of the ani­mals’ pro­tein ration. Most of the nitro­gen ingest­ed by a dairy cow, for exam­ple (via the pro­tein ration), is found in the milk, but also in the urine and fae­ces, thus con­tribut­ing to nitro­gen dis­charges and N2O emis­sions into the atmos­phere. Feed rations can there­fore be opti­mised by adjust­ing the pro­tein con­tent as much as pos­si­ble, or even using syn­thet­ic amino acids.

What potential do they offer?

In France, since the aware­ness of the prob­lems linked to the con­cen­tra­tion of nitrates in water, the opti­mi­sa­tion of ani­mal feed has already allowed for a lot of progress. In some ani­mal sec­tors it is now dif­fi­cult to do bet­ter. On a glob­al scale, how­ev­er, much progress can be made by opti­mis­ing ani­mal feed, in Chi­na for exam­ple, where inten­sive live­stock farm­ing has recent­ly developed.

How­ev­er, it has now been clear­ly demon­strat­ed that these means of opti­mi­sa­tion are not suf­fi­cient to achieve the objec­tives of the nation­al low-car­bon strat­e­gy (halv­ing emis­sions from agri­cul­ture by 2050). Ration opti­mi­sa­tion must be under­tak­en at the same time as reduc­ing the amount of ani­mal prod­ucts in our diet. The sci­en­tif­ic com­mu­ni­ty agrees that this has a cru­cial role in mit­i­gat­ing cli­mate change. There is already a down­ward trend in the con­sump­tion of ani­mal prod­ucts in West­ern coun­tries, and soci­ol­o­gists believe that this trend will continue.

Are these solutions consistent with all the mitigation measures for livestock farming? For example, of the role of cereals and oilseeds in reducing enteric fermentation in ruminants.

It is clear that these mea­sures, while ben­e­fi­cial at the ani­mal lev­el, should be con­sid­ered on a larg­er scale to assess their cli­mate foot­print. Many of them come up against lim­its fair­ly quick­ly, which is why reduc­ing the amount of ani­mal prod­ucts in human food is the most impor­tant mea­sure. I insist on this nec­es­sary change in our eat­ing habits. The worst thing would be to reduce live­stock farm­ing in France while con­tin­u­ing to eat as much meat as before so that we would need import it.

I think it is impor­tant to think on a region­al scale, by pro­mot­ing, for exam­ple, cir­cu­lar solu­tions that encour­age syn­er­gies between cere­al farms, live­stock farms and methani­sa­tion units. 

1Xu, X., Shar­ma, P., Shu, S. et al. Glob­al green­house gas emis­sions from ani­mal-based foods are twice those of plant-based foods. Nat Food 2, 724–732 (2021). https://doi.org/10.1038/s43016-021–00358‑x
2Accord­ing to the Glob­al Live­stock Envi­ron­men­tal Assess­ment Mod­el of the Food and Agri­cul­ture Orga­ni­za­tion of the Unit­ed Nations (accessed on 15 March 2022: https://​www​.fao​.org/​g​l​e​a​m​/​r​e​s​u​l​t​s/fr/